Comparative Analysis of Impact of OBD Organic and NPK Inorganic Fertilizers on Viability and Fungal Incidence in Maize (Zea mays) Seeds

Abstract

An experiment was conducted at the experimental site of the Institute of Agricultural Research and Training, Moor Plantation, Ibadan, Nigeria, to examine the effect of different combination levels of OBD organic-based and 300 kg/ha NPK fertilizers on viability and fungal incidence of harvested maize (Zea mays) seeds. Six treatment combinations of OBD and NPK fertilizers were applied as a split plot in a randomized complete block design with three replicates. The treatment levels were OBD-plus organic fertilizer at 5 t/ha (OBD5), 10 t/ha (OBD10) and 15 t/ha (OBD15), and in combination with NPK 15-15-15 mineral fertilizer applied at 300 kg/ha: OBD5NPK, OBD10NPK and OBD15NPK. Fertilizer NPK applied at 300 kg/ha served as the control treatment.

Twelve weeks after planting, the seeds were harvested, shelled, dried and stored for four weeks at room temperature. They were cultured weekly using the blotter method and scored for viability and fungal incidence, while the data collected were subjected to ANOVA using the GLM procedure of SAS. Isolated fungi included Aspergillus flavus, Aspergillus niger, Penicillium notatum, Mucor species and Fusarium verticillioides. Occurrences of Fusarium verticillioides and Aspergillus flavus were significantly higher than those of other fungi in that order (p ≤ 0.01, R² = 0.66). F-values for viability, isolated fungi, treatment, model, week of storage, interactions between treatment and fungi, and between week of storage and fungi were all highly significant (p ≤ 0.001).

Generally, fungal incidence in seeds treated with OBD only was significantly higher than in the control (NPK only). However, Fusarium verticillioides and Aspergillus niger in seeds treated with OBD only were significantly lower than in the control (p ≤ 0.05). Fungal incidence in seeds treated with OBD only was significantly lower than that in seeds treated with OBD and NPK (p ≤ 0.01, R² = 0.66). Viability (p ≤ 0.01, R² = 0.62) and fungal incidence in the seeds (p ≤ 0.01, R² = 0.66) increased significantly with increase in week of storage. During storage, viability of seeds treated with OBD only was significantly higher than that of seeds treated with OBD and NPK (p ≤ 0.01).

Thus, separate application of OBD fertilizer is strongly associated with lower fungal incidence in maize seeds and higher seed viability. Higher application rates of OBD fertilizer may be associated with increased viability and lower incidences of certain fungi in maize seeds. Appropriate use of OBD fertilizer alone in the field by farmers might sustain seed viability and appreciably reduce fungal incidence in maize seeds during long-term storage.